The present invention relates to display screens for combination sonar depth finders and mapping and/or position plotting devices. More particularly, the present invention relates to display screens configured to selectively provide a lower or higher resolution for simultaneous display of various types of information from combination sonar depth finders and mapping and/or position plotting devices.
Liquid crystal display (LCD) devices illuminate individual pixels in a matrix of pixels to provide an image on the display. LCD devices are often used in electronic devices such as calculators, computer display monitors, clocks, displays on microwave ovens, CD players, and marine sonar depth and fish finder devices. The number of pixels in the LCD matrix defines the resolution of the LCD. For sonar depth finder devices, a greater number of vertical pixels enables higher resolution of the images of underwater articles from which sonar echoes are returned. In addition to display of images representative of sonar echoes, some depth finder devices also display moving images representative of maps, such as water channels, rivers, and lakes, and associated land and island shore lines, and also plot the position and movement of a boat. Line and map drawing algorithms draw images in pixel representations that are organized for square pixels. Square pixels display images without distortion as well as being efficient for a computer processor to evaluate and control pixel illumination. The pixels in the LCD device accordingly have a 1:1 ratio of horizontal-to-vertical sizing. The display requirements of combination sonar depth finding and mapping and/or position plotting devices and such devices in combination with global positioning systems or other devices that can determine position thus have competing requirements for a higher resolution in a vertical dimension while needing square or 1:1 ratio pixels for mapping display requirements.
Accordingly, there is a need for an LCD display screen for combination sonar depth finders and mapping and/or position plotting devices that is configured to selectively provide a higher resolution in a vertical dimension for displaying images such as sonar images, and to selectively provide a lower two-dimensional resolution for simultaneously displaying images such as maps or position plots.